Population-based analysis of Actinobacillus pleuropneumoniae ApxIVA for use as a DIVA antigen

O’Neill, C. J.; Jones, Sophie; Bossé, Janine T.; Watson, Conrad; Williamson, Susanna; Rycroft, Andrew N.; Kroll, J. Simon; Hartley, H.M.; Langford, Paul R.

doi:10.1016/j.vaccine.2010.04.113

Cited by 10 publications

(5 citation statements)

References 25 publications

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“…To date, IS Apl1 has been identified only in serovars 2, 3, 6–8, 12, and 13. 11,12,16,18 The TSD nucleotide sequences, which were probably generated by insertion of IS Apl1 , differed between the 2 insertion types (i.e., the sequence was GC in strains QAS68, QAS93. and QAS102, and AA in strain FH24-1; Fig.…”

Section: Discussionmentioning

confidence: 99%

Nucleotide sequence analysis of a DNA region involved in capsular polysaccharide biosynthesis reveals the molecular basis of the nontypeability of two Actinobacillus pleuropneumoniae isolates

et al. 2016

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The aim of our study was to reveal the molecular basis of the serologic nontypeability of 2 Actinobacillus pleuropneumoniae field isolates. Nine field strains of A. pleuropneumoniae, the causative agent of porcine pleuropneumonia, were isolated from pigs raised on the same farm and sent to our diagnostic laboratory for serotyping. Seven of the 9 strains were identified as serovar 15 strains by immunodiffusion tests. However, 2 strains, designated FH24-2 and FH24-5, could not be serotyped with antiserum prepared against serovars 1-15. Strain FH24-5 showed positive results in 2 serovar 15-specific PCR tests, whereas strain FH24-2 was only positive in 1 of the 2 PCR tests. The nucleotide sequence analysis of gene clusters involved in capsular polysaccharide biosynthesis of the 2 nontypeable strains revealed that both had been rendered nontypeable by the action of ISApl1, a transposable element of A. pleuropneumoniae belonging to the IS30 family. The results showed that ISApl1 of A. pleuropneumoniae can interfere with both the serologic and molecular typing methods, and that nucleotide sequence analysis across the capsular gene clusters is the best means of determining the cause of serologic nontypeability in A. pleuropneumoniae.

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Section: Discussionmentioning

confidence: 99%

Nucleotide sequence analysis of a DNA region involved in capsular polysaccharide biosynthesis reveals the molecular basis of the nontypeability of two Actinobacillus pleuropneumoniae isolates

et al. 2016

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“…The expression of the apxIV has long been considered to be strictly induced in vivo, so pigs immunized with inactivated vaccines would not generate antibodies against ApxIV (11). Therefore, ApxIV antigen has been used to differentiate infected from vaccinated animals (DIVA), as it is immunogenic, specific to A. pleuropneumoniae, and encoded by all serovars (44). However, recently, an ApxIVA protein was identified for the first time from an in vitro growth of A. pleuropneumoniae as part of a subunit vaccine (45).…”

Section: Discussionmentioning

confidence: 99%

Simultaneous Detection of Antibodies against Apx Toxins ApxI, ApxII, ApxIII, and ApxIV in Pigs with Known and Unknown Actinobacillus pleuropneumoniae Exposure Using a Multiplexing Liquid Array Platform

Giménez-Lirola¹,

Jiang²,

Sun³

et al. 2013

Clin. Vaccine Immunol.

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c Surveillance for the presence of Actinobacillus pleuropneumoniae infection in a population plays a central role in controlling the disease. In this study, a 4-plex fluorescent microbead-based immunoassay (FMIA), developed for the simultaneous detection of IgG antibodies to repeat-in-toxin (RTX) toxins (ApxI, ApxII, ApxIII, and ApxIV) of A. pleuropneumoniae, was evaluated using (i) blood serum samples from pigs experimentally infected with each of the 15 known A. pleuropneumoniae serovars or with Actinobacillus suis, (ii) blood serum samples from pigs vaccinated with a bacterin containing A. pleuropneumoniae serovar 1, 3, 5, or 7, and (iii) blood serum samples from pigs with an unknown A. pleuropneumoniae exposure status. The results were compared to those obtained in a previous study where a dual-plate complement fixation test (CFT) and three commercially available enzyme-linked immunosorbent assays (ELISAs) were conducted on the same sample set. On samples from experimentally infected pigs, the 4-plex Apx FMIA detected specific seroconversion to Apx toxins as early as 7 days postinfection in a total of 29 pigs inoculated with 14 of the 15 A. pleuropneumoniae serovars. Seroconversion to ApxII and ApxIII was detected by FMIA in pigs inoculated with A. suis. The vaccinated pigs showed poor humoral responses against ApxI, ApxII, ApxIII, and ApxIV. In the field samples, the humoral response to ApxIV and the A. pleuropneumoniae seroprevalence increased with age. This novel FMIA (with a sensitivity of 82.7% and a specificity of 100% for the anti-ApxIV antibody) was found to be more sensitive and accurate than current tests (sensitivities, 9.5 to 56%; specificity, 100%) and is potentially an improved tool for the surveillance of disease and for monitoring vaccination compliance.

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“…Although our APP-RPA gave positive amplification for all 19 serovars, the apxIVA gene is not 100% conserved between isolates, and insertions such as ISApl1 have been detected in the apxIVA gene in some isolates, which could affect detection (34). When tested with isolates that have been found to have a transposase adjacent to or within their apxIVA genes, we found the isolate MIDG3936 with a WP_005599960 transposon flanking the apxIVA gene duplication (apxIVS') and a fragmented apxIVA gene, had a similar detection time to the reference serovar 2 strain.…”

Section: Discussionmentioning

confidence: 82%

Rapid Detection of Actinobacillus pleuropneumoniae From Clinical Samples Using Recombinase Polymerase Amplification

Stringer

Bossé

et al. 2022

Front. Vet. Sci.

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Actinobacillus pleuropneumoniae (APP) is the causative agent of porcine pleuropneumonia, resulting in high economic impact worldwide. There are currently 19 known serovars of APP, with different ones being predominant in specific geographic regions. Outbreaks of pleuropneumonia, characterized by sudden respiratory difficulties and high mortality, can occur when infected pigs are brought into naïve herds, or by those carrying different serovars. Good biosecurity measures include regular diagnostic testing for surveillance purposes. Current gold standard diagnostic techniques lack sensitivity (bacterial culture), require expensive thermocycling machinery (PCR) and are time consuming (culture and PCR). Here we describe the development of an isothermal point-of-care diagnostic test - utilizing recombinase polymerase amplification (RPA) for the detection of APP, targeting the species-specific apxIVA gene. Our APP-RPA diagnostic test achieved a sensitivity of 10 copies/μL using a strain of APP serovar 8, which is the most prevalent serovar in the UK. Additionally, our APP-RPA assay achieved a clinical sensitivity and specificity of 84.3 and 100%, respectively, across 61 extracted clinical samples obtained from farms located in England and Portugal. Using a small subset (n = 14) of the lung tissue samples, we achieved a clinical sensitivity and specificity of 76.9 and 100%, respectively) using lung imprints made on FTA cards tested directly in the APP-RPA reaction. Our results demonstrate that our APP-RPA assay enables a suitable rapid and sensitive screening tool for this important veterinary pathogen.

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Population-based analysis of Actinobacillus pleuropneumoniae ApxIVA for use as a DIVA antigen

Cited by 10 publications

References 25 publications

Nucleotide sequence analysis of a DNA region involved in capsular polysaccharide biosynthesis reveals the molecular basis of the nontypeability of two Actinobacillus pleuropneumoniae isolates

Nucleotide sequence analysis of a DNA region involved in capsular polysaccharide biosynthesis reveals the molecular basis of the nontypeability of two Actinobacillus pleuropneumoniae isolates

Simultaneous Detection of Antibodies against Apx Toxins ApxI, ApxII, ApxIII, and ApxIV in Pigs with Known and Unknown Actinobacillus pleuropneumoniae Exposure Using a Multiplexing Liquid Array Platform

Rapid Detection of Actinobacillus pleuropneumoniae From Clinical Samples Using Recombinase Polymerase Amplification

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